gnu: linux-initrd: Add (guix build linux-initrd) and use it.

* gnu/packages/linux-initrd.scm (qemu-initrd): Add #:modules argument.
  Factorize and move some of the code to...
* guix/build/linux-initrd.scm: ... here.  New file.
* Makefile.am (MODULES): Add it.

Makefile.am

@@ -61,6 +61,7 @@ MODULES =					\
   guix/build/cmake-build-system.scm		\
   guix/build/gnu-build-system.scm		\
   guix/build/gnu-dist.scm			\
+  guix/build/linux-initrd.scm			\
   guix/build/perl-build-system.scm		\
   guix/build/python-build-system.scm		\
   guix/build/utils.scm				\

gnu/packages/linux-initrd.scm

@@ -238,26 +238,17 @@ the Linux kernel.")
 (define-public qemu-initrd
   (expression->initrd
    '(begin
-      (use-modules (rnrs io ports)
+      (use-modules (srfi srfi-1)
-                   (srfi srfi-1)
                    (srfi srfi-26)
                    (ice-9 match)
-                   ((system foreign) #:select (string->pointer))
+                   ((system base compile) #:select (compile-file))
-                   ((system base compile) #:select (compile-file)))
+                   (guix build linux-initrd))
 
-      (display "Welcome, this is GNU/Guile!\n")
+      (display "Welcome, this is GNU's early boot Guile.\n")
       (display "Use '--repl' for an initrd REPL.\n\n")
 
-      (mkdir "/proc")
+      (mount-essential-file-systems)
-      (mount "none" "/proc" "proc")
+      (let* ((args    (linux-command-line))
-
-      (mkdir "/sys")
-      (mount "none" "/sys" "sysfs")
-
-      (let* ((command (string-trim-both
-                       (call-with-input-file "/proc/cmdline"
-                         get-string-all)))
-             (args    (string-split command char-set:blank))
              (option  (lambda (opt)
                         (let ((opt (string-append opt "=")))
                           (and=> (find (cut string-prefix? opt <>)
@@ -270,62 +261,33 @@ the Linux kernel.")
         (when (member "--repl" args)
           ((@ (system repl repl) start-repl)))
 
-        (let ((slurp (lambda (module)
-                       (call-with-input-file
-                           (string-append "/modules/" module)
-                         get-bytevector-all))))
         (display "loading CIFS and companion modules...\n")
-          (for-each (compose load-linux-module slurp)
+        (for-each (compose load-linux-module*
-                    (list "md4.ko" "ecb.ko" "cifs.ko")))
+                           (cut string-append "/modules/" <>))
+                  (list "md4.ko" "ecb.ko" "cifs.ko"))
 
-        ;; See net/slirp.c for default QEMU networking values.
+        (unless (configure-qemu-networking)
-        (display "configuring network...\n")
-        (let* ((sock    (socket AF_INET SOCK_STREAM 0))
-               (address (make-socket-address AF_INET
-                                             (inet-pton AF_INET
-                                                        "10.0.2.10")
-                                             0))
-               (flags   (network-interface-flags sock "eth0")))
-          (set-network-interface-address sock "eth0" address)
-          (set-network-interface-flags sock "eth0"
-                                       (logior flags IFF_UP))
-          (if (logand (network-interface-flags sock "eth0") IFF_UP)
-              (display "network interface is up\n")
           (display "network interface is DOWN\n"))
 
-          (mkdir "/etc")
-          (call-with-output-file "/etc/resolv.conf"
-            (lambda (p)
-              (display "nameserver 10.0.2.3\n" p)))
-          (sleep 1))
-
         ;; Prepare the real root file system under /root.
         (unless (file-exists? "/root")
           (mkdir "/root"))
         (if root
             (mount root "/root" "ext3")
             (mount "none" "/root" "tmpfs"))
-        (mkdir "/root/proc")
+        (mount-essential-file-systems #:root "/root")
-        (mount "none" "/root/proc" "proc")
+
-        (mkdir "/root/sys")
-        (mount "none" "/root/sys" "sysfs")
         (mkdir "/root/xchg")
         (mkdir "/root/nix")
         (mkdir "/root/nix/store")
 
         (mkdir "/root/dev")
-        (let ((makedev (lambda (major minor)
+        (mknod "/root/dev/null" 'char-special #o666 (device-number 1 3))
-                         (+ (* major 256) minor))))
+        (mknod "/root/dev/zero" 'char-special #o666 (device-number 1 5))
-          (mknod "/root/dev/null" 'char-special #o666 (makedev 1 3))
-          (mknod "/root/dev/zero" 'char-special #o666 (makedev 1 5)))
 
         ;; Mount the host's store and exchange directory.
-        (display "mounting QEMU's SMB shares...\n")
+        (mount-qemu-smb-share "/store" "/root/nix/store")
-        (let ((server "10.0.2.4"))
+        (mount-qemu-smb-share "/xchg" "/root/xchg")
-          (mount (string-append "//" server "/store") "/root/nix/store" "cifs" 0
-                 (string->pointer "guest,sec=none"))
-          (mount (string-append "//" server "/xchg") "/root/xchg" "cifs" 0
-                 (string->pointer "guest,sec=none")))
 
         (if to-load
             (begin
@@ -346,6 +308,7 @@ the Linux kernel.")
               (display "entering a warm and cozy REPL\n")
               ((@ (system repl repl) start-repl))))))
    #:name "qemu-initrd"
+   #:modules '((guix build linux-initrd))
    #:linux linux-libre
    #:linux-modules '("cifs.ko" "md4.ko" "ecb.ko")))
 

guix/build/linux-initrd.scm

@@ -0,0 +1,107 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2013 Ludovic Courtès <ludo@gnu.org>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (guix build linux-initrd)
+  #:use-module (rnrs io ports)
+  #:use-module (system foreign)
+  #:export (mount-essential-file-systems
+            linux-command-line
+            configure-qemu-networking
+            mount-qemu-smb-share
+            load-linux-module*
+            device-number))
+
+;;; Commentary:
+;;;
+;;; Utility procedures useful in a Linux initial RAM disk (initrd).  Note that
+;;; many of these use procedures not yet available in vanilla Guile (`mount',
+;;; `load-linux-module', etc.); these are provided by a Guile patch used in
+;;; the GNU distribution.
+;;;
+;;; Code:
+
+(define* (mount-essential-file-systems #:key (root "/"))
+  "Mount /proc and /sys under ROOT."
+  (define (scope dir)
+    (string-append root
+                   (if (string-suffix? "/" root)
+                       ""
+                       "/")
+                   dir))
+
+  (unless (file-exists? (scope "proc"))
+    (mkdir (scope "proc")))
+  (mount "none" (scope "proc") "proc")
+
+  (unless (file-exists? (scope "sys"))
+    (mkdir (scope "sys")))
+  (mount "none" (scope "sys") "sysfs"))
+
+(define (linux-command-line)
+  "Return the Linux kernel command line as a list of strings."
+  (string-tokenize
+   (call-with-input-file "/proc/cmdline"
+     get-string-all)))
+
+(define %host-qemu-ipv4-address
+  (inet-pton AF_INET "10.0.2.10"))
+
+(define* (configure-qemu-networking #:optional (interface "eth0"))
+  "Setup the INTERFACE network interface and /etc/resolv.conf according to
+QEMU's default networking settings (see net/slirp.c in QEMU for default
+networking values.)  Return #t if INTERFACE is up, #f otherwise."
+  (display "configuring QEMU networking...\n")
+  (let* ((sock    (socket AF_INET SOCK_STREAM 0))
+         (address (make-socket-address AF_INET %host-qemu-ipv4-address 0))
+         (flags   (network-interface-flags sock interface)))
+    (set-network-interface-address sock interface address)
+    (set-network-interface-flags sock interface (logior flags IFF_UP))
+
+    (unless (file-exists? "/etc")
+      (mkdir "/etc"))
+    (call-with-output-file "/etc/resolv.conf"
+      (lambda (p)
+        (display "nameserver 10.0.2.3\n" p)))
+
+    (logand (network-interface-flags sock interface) IFF_UP)))
+
+(define (mount-qemu-smb-share share mount-point)
+  "Mount QEMU's CIFS/SMB SHARE at MOUNT-POINT.
+
+Vanilla QEMU's `-smb' option just exports a /qemu share, whereas our
+`qemu-with-multiple-smb-shares' package exports the /xchg and /store shares
+ (the latter allows the store to be shared between the host and guest.)"
+
+  (format #t "mounting QEMU's SMB share `~a'...\n" share)
+  (let ((server "10.0.2.4"))
+    (mount (string-append "//" server share) mount-point "cifs" 0
+           (string->pointer "guest,sec=none"))))
+
+(define (load-linux-module* file)
+  "Load Linux module from FILE, the name of a `.ko' file."
+  (define (slurp module)
+    (call-with-input-file file get-bytevector-all))
+
+  (load-linux-module (slurp file)))
+
+(define (device-number major minor)
+  "Return the device number for the device with MAJOR and MINOR, for use as
+the last argument of `mknod'."
+  (+ (* major 256) minor))
+
+;;; linux-initrd.scm ends here